Brett, How did you determine it's an IM product?
What repeater/controller combination are you using? I'd try powering down the controller and manually keying the transmitter. If that solves it, it could be the controller's reference oscillator or divider outputs leaking onto the PTT line or elsewhere. Any compact fluorescent lights nearby? 73, Paul, AE4KR ----- Original Message ----- From: brett To: Repeater-Builder@yahoogroups.com Sent: Saturday, September 04, 2010 5:26 AM Subject: [Repeater-Builder] Interference on VHF repeater I have the distinctive hollow pipe sound. Both TX and RX have the same CTCSS tone. The intermod product is however not always present, and after looking at the RX output from the duplexer with a SA I see a comb of products that move slowly in time. When one of the products in the comb falls within the RX bandwidth the RX opens, until it moves on. This is not a busy site, and I have been able to power down everything on site except my repeater. Problem remains unchanged.